Shot-peening devices for projecting spherical particles, namely, shot particles, to the surface of a work piece to be treated, are known. Those devices include a nozzle-type device relevant to projecting the shot particles in relatively small volumes (e.g., Japanese Patent Early-Publication 2002-326161, assigned to the applicant) and an impeller-type device relevant to projecting them in relatively large volumes (e.g., Japanese Patent Early-Publication 11-239973).
An apparatus for a projection treatment equipped with a shot-penning device is one such as a shot-blasting machine or an air-blasting machine in which a workpiece is treated. In such an apparatus, the shot-penning device is mounted on a cabinet defining a projecting chamber therein. The shot-peening device projects short particles to a workpiece that is supported on a movable carriage. In such an apparatus, a circulation system for collecting the projected shot particles and returning them to the shot-peening device is also known (e.g., Japanese Patent Early Publication 59-187462 and the above-mentioned Japanese Patent Early-Publication 11-239973).
However, there is a problem in that the height of the apparatus disclosed in these publications is increased because a large circulation system is needed to collect the projected shot particles from the shot-peening device. In particular, in the shot-blasting machine with the impeller type shot-peening device, more particularly for the machine with plural devices, for projecting the shot particles in large volumes, the size of the circulation system is further increased and thus the machine needs the greater height. Accordingly, a large space is needed to install the blasting machine.
Further, the conventional circulation system in the blasting-machine is designed such that a collecting position in which the circulation system collects the shot particles that fall because of their own weight is located beneath the bottom end of a cabinet. Accordingly, a recess or a pit is needed in the area where the blasting machine is to be installed. Because the pit is located beneath the level of the floor or base on which the machine is to be installed, time and effort is necessary to construct such a pit.
Similarly, because the conventional blasting-machine is designed such that its lower portion to be received in the pit protrudes from the bottom end of the cabinet, the machine has an unstable stand when it is removed from the pit. Namely, such a design of the machine is inappropriate to transport and package the machine. To transport such an unstable machine, at least part of the machine should be reassembled. For example, to deliver the machine as the product to a user's factory from a manufacturer's firm, the following steps are needed. The machine is first trial assembled and temporarily installed to make a trial operation of it at the manufacturer's firm. Following the trial operation, the machine should be reassembled in order to transport it to the user's factory. In the factory, the delivered machine is re-assembled and installed, and this necessitates effort to construct the pit. Alternatively, say, any relocation of the user's factory means that the installed blasting machine should be transported to the new location and re-installed. In this case, the machine should be reassembled for transportation from the original location, and should be re-assembled and installed in a new location. This takes effort to construct the pit in the new location. Accordingly, it takes time and effort to both introduce a new machine and relocate it.